[PATCH] D22353: FileCheck Enhancement - CHECK-WORD

[Alexander Kornienko via llvm-commits]

alexfh added a comment.

In https://reviews.llvm.org/D22353#541171, @eklepilkina wrote:

> > What are our options with the regex library? Is there a newer version of the one we are currently using that we could upgrade to (and that supports \b)?
>
>
> As I understood used regexp library is version of OpenBSD library. I couldn't find some new versions.
>  I don't know a lot about modern C++ regexp library, but there are:
>
> 1. PCRE(pcre.h)
> 2. There is regex library in boost. But boost is too big
> 3. Also there is regex library in poco.


FWIW, there's also re2 (https://github.com/google/re2).

> May be there are people who has some experience with C++ regexs libraries.

> 

> > How much work would it be to implement support for \b ourselves?

> 

> 

> I can't give exact estimate. I inly had a look on its source code. But I think that it's wrong to add features support. There are a lot of other useful feautures, for example complex assertions, conditional subexpressions and etc., that can be used. Then if somebody want them he should implement them by himself.




In https://reviews.llvm.org/D22353#536766, @eklepilkina wrote:

> In https://reviews.llvm.org/D22353#535691, @alexfh wrote:
>
> > Why not add more words to check lines to make them more strict?
>
>
> This patch adds
>
>   // CHECK-WORD:
>   // CHECK-WORD-NEXT:
>   // CHECK-WORD-SAME:
>   // CHECK-WORD-DAG:
>   // CHECK-WORD-NOT:
>   
>
> What words do you suggest to add?


I'm suggesting to make patterns used in CHECK-lines stricter by adding more text to them instead of allowing to match on word boundaries using the new CHECK-directives. E.g. the line you want to check is

  op1;

So instead of using `CHECK-WORD: op1`, you could make the pattern stricter by adding more context: `CHECK: {{^}}op1;{{$}}`. Do you have specific examples of output and patterns, where this solution is undesired for some reason?

Overall, I think the FileCheck utility is already confusing enough and many developers attribute some magic properties to it (that it can somehow implicitly connect position of a CHECK line to the position of the relevant line in the input, etc.). Adding more features like CHECK-WORD only makes this worse.

> > So is it feasible to add support for \b to LLVM regexps?

> 

> 

> The regexp library is very old. I asked several times about changing it. But I haven't got any answer. There are a lot of other unsupported features of regexs in this library and which can be useful.





https://reviews.llvm.org/D22353